Allocation - North Carolina State University

Report
Environmental Life Cycle Assessment
PSE 476/WPS 576/WPS 595-005
Lecture 10A: Allocation
Fall 2014
Richard A. Venditti
Forest Biomaterials
North Carolina State University
Raleigh, NC 27695-8005
[email protected]
Go.ncsu.edu/venditti
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Allocation
• Allocation: partitioning the input and
output flows of a process or a product
system between the product system under
study and one or more of the other product
systems
(ISO 14044: 2006E)
Allocation Procedures
• Step 1: allocation should be avoided
– Increasing the level of detail. By dividing the
unit process into 2 or more sub-processes
and tracking data for both separately
– System Expansion. Expanding the system to
include the additional functions of the related
co-products
Refs: Michael Hauschild, DTU
Allocation Procedures
• Step 2: partition the inputs and outputs
between products in a way that reflects
underlying physical relationships
– Number of parts
– Mass
– Volume
• Step 3: partition the inputs and outputs
between products in a way that reflects other
relationships between them
– economic value
Refs: Michael Hauschild, DTU
Avoidance of Allocation:
Divide the process
• A factory makes television sets and also makes car radios.
The factory utilizes 50,000 kWh every month. The electrical
power used during days in which tv manufacture occurs is
twice the amount than when radios are being made. In an
month 8000 tv’s and 2000 radios are produced on average.
What is the amount of electricity that can be attributed to a tv
and a radio? The factory is closed on weekends.
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Avoidance of Allocation:
Divide the process
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Avoidance of Allocation:
System Expansion
• A landfill disposes of 50 tons of waste by burning and
produces 550 kWh per ton. The process emits a total of 400 kg
of CO2e per ton of waste burnt. Use system expansion to
determine the emission per ton of waste processed for the
following cases for the alternate source of electricity:
– Anthracite coal
– Natural Gas
– Biodiesel
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Avoidance of Allocation:
System Expansion
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Allocation Issues: Co-products:
• Co-products Allocation: a single process produces
multiple products,
– Burdens can be partitioned by mass flows, volume flows,
piece flows monetary values….
– Must use process/product knowledge to determine
partioning method
– Example for paper production: paper, Tall Oil, turpentine,
electricity…
Emissions
Raw Matls
Power
Product B
System
Product A
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Allocation Issues: Co-products:
• A truck travels 800 km delivering 10,000 kg of food.
The truck has the following emission .094 kg
CO2e/tonne km. The following is transported:
– 800 packages of spices, 0.5 kg per bag, price: $800/kg
– 8000 packages of flour, 1 kg per bag, price $30/kg
– 400 packages of rice, 4 kg per bag, $1/kg
• Use allocation procedures to allocate the emission. Determine
the emission per kg of each food product also.
– By bag
– By mass
– By value
Allocation Issues: Co-products:
• Total emissions:
• Total bags:
• Total Mass:
• Total Value:
Allocation Issues: Co-products:
Item Allocation
Allocation
Factor
Spice
Flour
Rice
Allocated Flow, Emission kg
kg CO2e
CO2e /bag
Emission kg
CO2e /kg food
Allocation Issues: Co-products:
Mass Allocation
Allocation
Factor
Spice
Flour
Rice
Allocated
Flow, kg
CO2e
Economic Allocation
Emission kg Allocation
CO2e /kg
Factor
food
Allocated
Flow, kg
CO2e
Emission kg
CO2e / kg
food
Allocation Issues: Recycling
•
Recycling Allocation: a virgin product is recycled or re-used in a subsequent
life (Hitchhikers guide to LCA, Baumann and Tillman, 2004)
– There exists operations that are required by the virgin and the recycled products
(shared operations)
– Example shared operations: virgin raw material production, final disposal
– Many ways to allocate the burdens of the common operations
Primary material
production
(V1)
Production of
Product P1
(P1)
Use of
Product P1
(U1)
Recycling of
Product P1
(R1)
Production of
Product P2
(P2)
Use of
Product P2
(U2)
Recycling of
Product P2
(R2)
Production of
Product P3
(P3)
Use of
Product P3
(U3)
End of life
(W3) 14
Allocation Issues: Recycling:
•
Cut off method: loads directly caused by a product are assigned to
that product (V1 to L1, R1 to L2, R2 and W3 to L3)
•
Approximation with closed loop recycling. Equal burdens. All
lives of a product share equal the shared operation loads.
•
Relative loss of quality: shared operation loads partitioned
according to quality of products
•
Waste treatment is inevitable consequence of raw material
extraction (V1 and W3 to L1)
•
Man made products are valuable that must be replaced by virgin
resources if lost as waste (V1 and W3 to L3)
Allocation Issues: Recycling
•
Use cut off, approx. of closed loop, and quality methods to calculate
emissions of each product
•
R1=R2= 3 units of emissions,
•
W3=1 unit of emissions
•
Relative quality of products: Q1=1, Q2=0.75, Q3=0.5
U1=U2=U3=0
Primary material
production
(V1)
Production of
Product P1
(P1)
Use of
Product P1
(U1)
Recycling of
Product P1
(R1)
Production of
Product P2
(P2)
Use of
Product P2
(U2)
Recycling of
Product P2
(R2)
Production of
Product P3
(P3)
Use of
Product P3
(U3)
End of life
(W3) 16
Allocation Issues: Recycling
•
Use cut off, approx. of closed loop, and quality methods to calculate
emissions of each product
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Summary
•
•
•
•
Coproducts
System expansion
Divide the process
Allocation
–
•
•
•
•
•
•
•
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Item, physical quantity, other quantity
Allocation factor
Allocated emissions
Recycling
Shared operations
Cut off
Loss of quality
Equal burdens

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